Process for removing the hair from green hides



' sulphide:

Patented Sept. v7, 1926."

UNITED STATES PATENT OFFICE.

mix nnnemxnn, nuenn mmnnnonrna, AND ALICE nmnnnonrnn, min ooonson,

- or mmsnnn, enrmnnr.

rnocnss non nnmovme THE .nnm rnoni GREEN nrnns.

No Drawing. Application filed September 13, 192*, Serial No. 737,607,and in Germany September 19, 1923. i

It has become known to use alkalior earth alkali sulphides for removingthe hair from green hides. It is further known to use forthe samepurpose nitrogen bases like ammonlaalone, for instance in closedchamhers and in the heat. The first mentioned process more or lessaffects the hair especially the wool, and the last mentioned proc'.esses are cumbersome and require expensive installations It has furtherbeen roposed to use a mixture of sodium sulp ids and of sodiumsulplihydrate' to which such uantities of ammonia carbonate are added,

t at the sodium sulphhydrate is converted into-equal parts of sodiumsulphide and of ammonia sulphide. Consequently in this process alsoconsiderable quantities of active sulphide pr sodium remain present andexert their unfavorable, decomposing action on the hair, at the roots aswell as at the parts exposed above the skin.

' We now have found'that the above stated inconveniences can beavoidedby using sulphides of inorganic or organic. nitrogen bases which arefree from active alkali sulused for the slackening process, said liquidsno more containing any active free alkali Further we have .found that anunhairing liquid, combined from solutions of ammo nia sulphide andsoluble silicates, is specially well suited for this purpose. 'A liquidofquestion and to t e desired leather to be obtained.

this kind frees the hides and skins from hair within-a few hours anddoes not afiect I the valuable skin substancenor the hair.

- Emamples. 1.To,free iieec es frdm wool the slacken ing liquid isprepared as "follows:

20 liters of commercial ammonia sulphide,

.50 200 liters of aqueous ammonia,solution (of 0.910 spec. gravity) and-20 hectoliters of.

water are mixed to 'ethen Into this solution the corresponding quantityof sheep-' skins or" fleeces is immersed, the quantity of thanindicated.

steeping liquid amounting for instance to 155 five times the weight ofthe hides. The temperature is preferably maintained at 25 C.,'

and after 1 to 2 days the skins will release the hair quite readily. Thewool remains 1n a very good condition.

2.Instead' of the free ammonia the 'corresponding quantity of pyridin of1' liter of technical pyridin for one liter or M sulphide.- Thecomposition mayvary con- 7 siderably and be, without prejudice, strongerSo much of thisgunhairing liquid is used that the hides are wellcovered. .After 5 tot hoursalready, the mass having been agitatedrepeatedly, the hides will let loose the hair readily, this loosening ofthe hair being further improved within 1 to 2 days. The skin is notafiected at all but comes out of the process at a very clear state. Thewoolis'of excellent softness and good touch and proves tocontain theelastin yet in unaltered state. It difl'ers not in the least 4 from goodfleecing.-

The treatment of other kinds of hides may 00 I be carried out in asimilar manner, with convenient modificatio of theprocess. ,In all thesecases the working prescriptions for the unhairing process must beadapted to t e special working rocess of the tannery in quality for theInstead of ammonia sulphide sueh salt mixtures may be employed whichwhen dis-- solved will form ammonia sulphide, .{s for ing in immersingthe hides in a solution containing sulphides of nitrogen bases and beingfree of active alkali sulphide.

2. A process .for unhairing hides consisting in immersing the hides in asolutioncontaining sulphides of inorganic nitrogen bases and being freeof active alkali sulphide.

3. A process for unhairing hides consisting in convertingalkali'sulphide with at least the equimolecular quantity of salts ofnitrogen bases into sulphides of said nitrogen bases, and immersing thehides in the solution thus obtained.

4. A process for unhairing hides consisting in converting alkalisulphide with at least the equimolecular quantity of salts of inorganicnitrogen bases into sulphides of said inorganic nitrogen bases, andimmersing the hides in the'solution thus obtained.

5. A process for unhairinghides consisting in immersing the hides in asolution containing sulphides of nitrogen bases and soluble silicates. I

6. A process for unhairing hides consist ing in .immersin the hides in asolution containing sulplii es of inorganic nitrogen bases and solublesilicates.

' 7. A process for unhairing hides consist.- ing in immersing the hidesin a solution contaming ammonium sulphide and'a soluble silicate. 8. Aprocess tor unhairing hides consisting in converting alkali sulphidewith at least the equimolecular quantity of ammoniasalt into ammoniumsulphide, adding a soluble silicate thereto, and immersing the hides inthe solution thus obtained.

In testimony whereof we have hereunto set our hands.

Prof. MAX BERGMANN. Dr. EUGEN IMMENDGRFER.

Dr. ALICE lMMENDdRFER, ne GOODSON. i

